1. Field of the Invention
The present invention relates to a flow path opening/closing valve for switching a flow through state of a fluid by opening and closing a flow path through which the fluid flows.
2. Description of the Related Art
Heretofore, a flow path opening/closing valve has been known which, for example, is connected to a flow path through which a fluid flows, and which controls a flow through state of the fluid by switching a state of communication of the flow path.
As a flow path opening/closing valve of this type, in U.S. Pat. No. 4,815,704, there is disclosed a “ball valve” structure having a spherical valve. In the flow path opening/closing valve, a valve chamber is provided, which accommodates therein the spherical valve in the interior of a valve main body. By rotating a shaft, which is connected to an upper portion of the valve, a through hole of the valve establishes communication between a pair of passages (fluid inlet port and fluid outlet port) formed in the valve main body. Annular seal members are provided on the side of the fluid inlet port and the side of the fluid outlet port of the valve, which function as valve seats for supporting the valve, and slide against the outer circumferential surface of the valve to prevent fluid from leaking into the interior of the valve chamber.
Further, U.S. Patent Application Publication No. 2008/0283787 discloses a “ball valve”. As shown in FIG. 5, seal members 4a, 4b have a pair of curved surfaces and are arranged in the interior of a first body 2a. End surfaces of the seal members 4a, 4b abut against each other such that the seal members 4a, 4b sandwich therebetween a spherical valve body 6 in which the fluid passage is formed. The spherical valve body 6 slides against the curved surfaces and is retained rotatably. O-rings 8a, 8b are provided respectively on surfaces of the seal members 4a, 4b, which face toward the fluid inlet port and the fluid outlet port. The second body 2b is fitted into the first body 2a, and by the second body 2b pressing the o-ring 8b, the seal members 4a, 4b are pressed into contact, whereby a sealing effect is carried out in cooperation with the o-ring 8a. 